Electric circuit for an access control and for an immobilizer of a vehicle and method for calibrating an antenna driver

Abstract

An electric circuit for controlling the access and immobilizing a vehicle has a first antenna driver ( 12 ) for driving a first antenna ( 19 ) for emitting a signal ( 100 ) in the event of identification of an ID transmitter ( 3 ) for access control of a vehicle. A second antenna driver ( 24 ) is provided for driving a second antenna ( 21 ) for emitting a signal ( 104 ) in the event of identification of an ID transmitter ( 3 ) for the immobilizer of the vehicle. In addition, the electric circuit has a receiver device ( 14 ) for receiving a signal captured by an antenna ( 21 ) for the identification of an ID transmitter ( 3 ) for the immobilizer. The first antenna driver ( 12 ) and the receiver device ( 14 ) are commonly integrated into a semiconductor chip ( 1 ).

What is claimed is: 
     
       1. An electric circuit for an access control and for an immobilizer of a vehicle, comprising:
 a first antenna driver for driving a first antenna for sending a signal on identification of an ID transmitter for the access control of the vehicle, 
 a second antenna driver for driving a second antenna for transmitting a signal on identification of an ID transmitter for the immobilizer of the vehicle, 
 a receiver device for receiving a signal received by an antenna for identifying an ID transmitter for the immobilizer, 
 a third antenna driver for driving a third antenna on identification of the ID transmitter for the access system of the vehicle, 
 wherein the first antenna driver, the second antenna driver, the receiver device, and the third antenna driver are integrated onto a single semiconductor chip, and 
 wherein characteristics of the first antenna driver and the third antenna driver are independently controllable during simultaneous operation of the first and third antenna drivers. 
 
     
     
       2. The electric circuit according to  claim 1 , further comprising a diagnosis circuit in the semiconductor chip for calibrating the signal sent by the first antenna, with at least one input of the diagnosis circuit being connected to an output of the receiver device. 
     
     
       3. The electric circuit according to  claim 2 , further comprising a calibration circuit for calibrating the first antenna driver, with the calibration circuit having at least one input which is connected to an output of the diagnosis circuit. 
     
     
       4. The electric circuit according to  claim 1 , wherein a control circuit of a boost converter is also accommodated in the semiconductor chip. 
     
     
       5. The electric circuit according to  claim 1 , comprising the first antenna and the second antenna. 
     
     
       6. The electric circuit according to  claim 1 , comprising a synchronization output for outputting a reference clock to synchronize with at least one further semiconductor chip. 
     
     
       7. The electric circuit according to  claim 1 , comprising a switchover device with which the connection between antenna drivers and antennas or between the receiver device and antennas can be switched over. 
     
     
       8. A method comprising:
 providing an electrical circuit comprising a first antenna driver for driving a first antenna for sending a signal on identification of an ID transmitter for an access control of a vehicle, a second antenna driver for driving a second antenna for transmitting a signal on identification of an ID transmitter for an immobilizer of the vehicle, a receiver device for receiving a signal received by an antenna for identifying an ID transmitter for the immobilizer, and a third antenna driver for driving a third antenna on identification of the ID transmitter for the access system of the vehicle, wherein the first antenna driver, the second antenna driver, the receiver device, and the third antenna driver are integrated onto a single semiconductor chip, 
 using the electrical circuit in the vehicle, and 
 independently controlling characteristics of the first antenna driver and the third antenna driver during simultaneous operation of the first and third antenna drivers. 
 
     
     
       9. A method for calibrating an antenna driver for an electric circuit comprising a first antenna driver for driving a first antenna for sending a signal on identification of an ID transmitter for an access control of a vehicle, a second antenna driver for driving a second antenna for transmitting a signal on identification of an ID transmitter for an immobilizer of the vehicle, a receiver device for receiving a signal received by an antenna for identifying an ID transmitter for the immobilizer, and a third antenna driver for driving a third antenna on identification of the ID transmitter for the access control of the vehicle, wherein the first antenna driver, the second antenna driver, the receiver device, and the third antenna driver are integrated onto a single semiconductor chip, the method comprising:
 a) operating the first antenna driver so that the first antenna transmits a low-frequency signal, 
 b) receiving the low-frequency signal by means of the second antenna and of the receiver device, 
 c) diagnosing the received signal. 
 
     
     
       10. The method according to  claim 9 , further comprising:
 d) Adjusting the first antenna driver in accordance with a setpoint value. 
 
     
     
       11. The method according to  claim 9 , wherein, in step c) the received signal is diagnosed in relation to a frequency, a signal-to-noise ratio or a signal strength. 
     
     
       12. The method according to  claim 9 , wherein, in step d) a current output by the first antenna driver is adjusted. 
     
     
       13. The method according to  claim 9 , wherein calibration is controlled by a diagnosis circuit in the semiconductor chip, with at least one input of the diagnosis circuit being connected to an output of the receiver device. 
     
     
       14. The method according to  claim 13 , wherein the electric circuit further comprises the third antenna driver for driving the third antenna on identification of the ID transmitter for the access system of the vehicle, and the method further comprises setting the characteristics of the first antenna driver and of the third antenna driver independently of one another during simultaneous operation. 
     
     
       15. The method according to  claim 9 , wherein a control circuit of a boost converter is also accommodated in the semiconductor chip. 
     
     
       16. The method according to  claim 9 , wherein the electrical circuit comprises the first antenna and the second antenna. 
     
     
       17. The method according to  claim 9 , comprising outputting a reference clock to synchronize with at least one further semiconductor chip.